EUROPEAN JOURNAL OF NATURAL HISTORY 4 2015

32 Technical sciences

Fig 22 1D convection equation with source term auх = сos(x) on [0 π] and a = 1

conclusionsthe best criterion for evaluate a numerical meth-

od is the results of the method and as can be seen in the examples were solved the result of RFEM comparable to the best results were obtained by other methods is (for these examples because of the small size of the elements the difference between the re-sults from different methods can not be seen) and given that the system of equations resulting from this approach similar (in terms of density) Finite Differ-ence Method (FDM) is its efficiency can be com-pared with finite difference methods (although the use of the Legendre shape functions gives an effi-ciency much higher than FDM) so do not think other methods that are used in cFD be able to compete with it Also due to the similarity of relations many of the techniques used in the FDm can be used to rFem [hoffmann and chiang (1998)]

References1 Zienkiewicz oc and morgan K Finite elements and

Approximation John Wiley amp Sons 19832 Zienkiewicz OC and Taylor RL The Finite Element

method volume 1 the basis butterworth-heinemann 20013 Laney CB Computational Gasdynamics Publisher

Cambridge University Press Pub Date June 28 19984 Hughes TJR Cottrell JA Bazilevs Y ldquoIsogeometric

analysis CAD finite elements NURBS exact geometry and mesh refinementrdquo Computer Methods in Applied Mechanics and Engineering 194(39ndash41) Р 4135ndash4195 2005

5 Hoffmann KA and Chiang ST Computational Fluid Dynam-ics Vol I and II 3rd edition Engineering Education System (1998)

6 Deng J Chen F Li X Hu C Tong W Yang Z and Feng Y Polynomial splines over hierarchical T-meshes Graph Models 70(4)76ndash86 2008

the work is submitted to the international sci-entific Conference ldquoEngineering science and mod-ern manufacturerdquo France October 18ndash25 2015 came to the editorial office оn 13082015

reseArch oF inFluence OF MICRO-ARC OXIDATION MODES

on oxiDe coAting propertiesramazanova Zm mustafa lm

Joint-Stock Company ldquoNational Center of Space Research and Technologyrdquo Almaty

e-mail zhanat2005yandexkz

Currently search for new efficient coatings with high wear resistance corrosion resistance thermal resistance for spare parts of machines and mecha-nisms of different purpose is an ongoing process Due to the above a comparatively new method for treatment of valve metals surface ndash micro-arc oxi-dation method ndash is of interest this method allows obtaining fundamentally new coatings which are characterized through different physical chemical and mechanical properties pulse mode of perform-ing micro-arc oxidation is of great interest When forming oxide coating under the pulse mode by mi-cro-arc oxidation method the value of current anode pulse duration has a significant impact on rough-ness of the coating The work studies influence of current anode pulse duration on properties of oxide coating obtained by micro-arc oxidation method

Aluminum titanium zirconium alloys and other materials are widely used as structural materials in modern engineering and airspace industry Search for new efficient coatings with high wear resistance corrosion resistance thermal resistance for spare parts of machines and mechanisms of different pur-pose is an ongoing process Due to this micro-arc oxidation method (MAO) [1ndash3] which is compara-tively new method for treatment of valve metals is of interest the method allows obtaining brand new coatings with unique complex of properties charac-terized through high performance indicators the

EUROPEAN JOURNAL OF NATURAL HISTORY 4 2015

33Technical sciences

peculiarity of micro-arc oxidation method is that the process runs under high electric field intensity and is accompanied by formation of micro-plasma and micro-regions with high pressure due to appearing gases which leads to developing of high tempera-ture chemical transformations and transportation of the substance in the arc micro-plasma charges activ-ity results in formation of coating layer consisting of oxidized forms of metal elements of electrolyte basis and components The coating basis predominantly consists of α-Al2o3 (corundum) [3]

Topical is the issue of obtaining oxide coating in MAO mode with low roughness in order to exclude additional mechanical treatment of surface layer

In this regard research of influence of current anode pulse duration on properties of oxide coat-ings obtained by micro-arc oxidation method is of interest

Materials and methods samples for appli-cation of oxide coating were made out of A0 alu-minum with dimensions of 2x2 cm and thickness of 3 mm area of the surface to be treated was 8 cm2 The samples prior to application of oxide coating by mAo method underwent mechanical polishing and had roughness of Ra = ndash 0098 μm

Oxide coating was formed in electrolyte so-lution consisting of gl Na2hpo4middot12Н2О ndash 40 na2b4o7middot10 Н2О ndash 30 H3bo3 ndash 20 naF ndash 10 Electrolyte was prepared out of distilled water and analytically pure and chemically pure reagents Mi-cro-arc oxidation was carried out in a 700 ml capac-ity tub made of stainless steel With the purpose of cooling the electrolyte the tub was provided with water cooling system Tub body served as cathode in the process of mAo

mAo process was performed using pulse power source which allowed obtaining voltage pulses of rec-tangular trapezoidal form with pulses flow frequency of 50 Hz and current density of 114ndash130 Adm2

roughness of coatings was measured with ap-plication of proximity MICRO MEASURE 3D sta-tion 3D-profiler Micro-hardness of coatings was identified by means of Nano Hardness Tester by in-denting the penetrator with diamond tip under max-imum load of 20 mn wear resistance of coating was measured on high temperature friction gauge THT-S-AX0000 Identification of coating durabil-ity was based on friction principle of ball indentor made of ВК alloy against surface Whereas the load was equal to 1N linear velocity ndash 25 cms meas-urements were taken under temperature of 250 degc 50 air humidity Durability value was identified by track area measured on three-dimensional profil-er using mountains map universal software and ob-taining three-dimensional images of sample surface with track For each sample 9 values of track area were obtained and arithmetic average was found Coatings thickness was measured on QuaNix-1500 thickness gauge the thickness was calculated as an average among 15 measurements from both sides of the sample Porosity form distribution of pores

by dimension were analyzed by processing micro-photos of surface of samples being studied which photos were obtained on Quanta 200i 3D raster type electronic microscope using planimetry secant and dots methods as a ratio of pore image area to total area of a section under observation [4]

Discussion of results conducting of mAo process in constant current mode causes intense warming up of near-electrode layer which leads to formation of partial melting on the sample surface destruction and peeling of coating formation of coatings with high roughness

It is known that when forming oxide coating by micro-arc oxidation method in the pulse mode the value of current anode pulse duration has a sig-nificant impact on coating roughness [5] In case the process is carried out with small values of cur-rent anode pulse duration the micro-arc charges arise during short period of time in this case the material under treatment is not overheated and in the interval between pulses the heat is able to flow to the solution small values of pulse duration lead to appearance of small oxide buildups and to sig-nificant quantity of pores per unit of area This fa-cilitates formation of uniform coatings with low roughness

Voltage value influences final thickness of the coating values of current anode pulse duration in-fluences coating quality in particular roughness thereof whereas pulse amplitude influences the coating formation rate changes of thickness and roughness of coatings formed under polarizing volt-age Up = 300V under different duration of current anode pulse are in table 1

As it is seen from the obtained data with increase in current anode pulse duration the coating thickness grows coating roughness increases the latter is re-lated to the fact that with growth of coating thickness increases power intensity of micro-plasma charges whereas increase in dimensions of individual micro-arc charges is observed warming up takes place in near-electrode layer of the solution

In the process of study of these coatings for wear resistance (durability) three dimensional im-ages of samples surface with track were obtained on these pictures it is seen that track width of initial sample without coating exceeds the width of tracks of samples with oxide coating obtained under dif-ferent current anode pulse duration

track areas values for samples without coating and with oxide coating are shown in form of a dia-gram in figure

As it is seen from the diagram track areas of samples with oxide coating are significantly less than track area of initial sample which testifies of high wear resistance of samples with oxide coat-ing As anode pulse duration increases with coat-ing thickness growth the coating wear resistance increases since coating roughness is related to fric-tion ratio along with roughness increase friction ratio increases as well (table 2)

EUROPEAN JOURNAL OF NATURAL HISTORY 4 2015

34 Technical sciences

Table 1Dependence of thickness and roughness of coatings on current anode pulse duration

current anode pulse duration ms time min Coating thickness μm Roughness Ra μm1 50 20 78 0342 100 20 111 0573 150 20 197 0924 200 20 265 221

Track areas values when performing durability test of samples without coating and with oxide coating obtained under different durations of current anode pulse 1 ndash initial sample 2 ndash 50 ms 3 ndash 100 ms 4 ndash 150 ms 5 ndash 200 ms

Table 2micro-hardness of coating

polarizing voltage v current anode pulse duration ms micro-hardness mpa Friction ratio1 300 50 15227 0852 300 100 18882 1123 300 150 37757 2164 300 200 335439 368

An important physical and mechanical feature of coating is its micro-hardness micro-hardness values on surface of samples depending on coating obtainment modes are shown in table 2

Study of micro-hardness deep into the sample showed that in the MAO process a transient layer deep into the metal is generated from oxide layer with gradual decrease of micro-hardness value For instance when pulse duration is 100 ms the micro-hardness of transient layer gradually decreases from 10474 MPa to 8462 MPa when measuring at depth of 15 to 40 μm deep into the metal Micro-hardness of initial material is equal in this case to around 150 mpa in this depth interval also young module increase is observed which is below 89 Gpa in av-erage whereas initial material has young module of 70 Gpa

Research of coating surface morphology by means of raster electronic microscope showed that with 50 ms anode pulse duration a thin coating is formed due to low productivity of the process Whereas formation of basic external functional layer is not complete coating is formed in spots with current anode pulse duration of 50 ms forma-tion of significant quantity of round shaped pores per unit of surface area is observed As current an-ode pulse duration increases to 200 ms the nature of micro-plasma charges change small spark charges are replaced with large ones coating thickness growth leads to of refilling pores quantity of pores decreases As a result of spark charges enlargement the average dimension of pores increases with cur-rent anode pulse duration of 200 ms surface poros-ity values are shown in table 3

EUROPEAN JOURNAL OF NATURAL HISTORY 4 2015

35Technical sciences

conclusionsimpact of current anode pulse duration on prop-

erties of oxide coatings has been studied It has been shown that current anode pulse duration has signifi-cant impact on coating roughness As pulse duration increases coating roughness friction ratio increase as well

tribometric research of coatings showed that as a result of micro-arc oxidation durable coatings are formed whereas with increase of anode pulse duration and thickness of coating the durability of the coating increases micro-hardness on coating thickness of 197 and 265 μm is equal to 38 and 335 GPa respectively It has been found out that as a result of micro-arc oxidation a transient layer is formed deep into the metal with high value of micro-hardness in comparison with untreated alu-minum Micro-hardness of transient layer is gradu-ally decreasing deep into the metal

Authors of the article express thanks to Profes-sor Mamayev AI as well as to the Center for ma-terial properties research of the physical-technical institute of Tomskiy polytechnic university to Ka-zakhstan national university named after Al-Farabi for conducting tests of obtained oxide coatings

the work has been performed within frames of grant financing by the Republic of Kazakhstan Min-istry of Education and Science

References1 Kurze P et all Micro Arc Spark Anodizing ndash was ist

das Micro Arc Spark Anodizing ndash what is that Galvanotech-nik 2003 ndash 8 ndash Р 1850ndash1863

2 Mamayev AI Mamayeva VA Intense current pro-cesses in solutions of electrolytes ndash Novosibirsk Edition of Sybirian Department of Russian Academy of Science 2005 ndash 255 p (russ)

3 Suminov IB Epelfeld AB Lyudin VB and other Mi-cro-arc oxidation Theory technology equipment M ECOM-ET 2005 ndash 368 p (Russ)

4 Saltykov SA Stereometric metallography ndash M Metal-lurgy 1970 ndash 375 p (Russ)

5 Chubenko AK Mamayev AI Budnitskaya YY Doro-feyeva TI Role of current pulse duration as a factor of controlling physical and mechanical characteristics of anode-oxide coatings using the example of Д16 aluminum alloy Scientific-technical newsletter of Volga region ndash 2013 ndash 2 ndash Р 62ndash64 (Russ)

the work is submitted to the international sci-entific Conference ldquo Manufacturing technologiesrdquo itAly (rome Florence) september 5ndash12 2015 came to the editorial office оn 11082015

Table 3Surface porosity of oxide coatings

current anode pulse duration ms

coating thick-ness μm

Porosity ΔS Quantity of pores per 1 cm2 of coating

Average diameter of pores μm

1 50 78 64 11106 2722 100 111 117 73105 453 150 197 56 35105 454 200 265 87 302105 606

EUROPEAN JOURNAL OF NATURAL HISTORY 4 2015

33Technical sciences

peculiarity of micro-arc oxidation method is that the process runs under high electric field intensity and is accompanied by formation of micro-plasma and micro-regions with high pressure due to appearing gases which leads to developing of high tempera-ture chemical transformations and transportation of the substance in the arc micro-plasma charges activ-ity results in formation of coating layer consisting of oxidized forms of metal elements of electrolyte basis and components The coating basis predominantly consists of α-Al2o3 (corundum) [3]

Topical is the issue of obtaining oxide coating in MAO mode with low roughness in order to exclude additional mechanical treatment of surface layer

In this regard research of influence of current anode pulse duration on properties of oxide coat-ings obtained by micro-arc oxidation method is of interest

Materials and methods samples for appli-cation of oxide coating were made out of A0 alu-minum with dimensions of 2x2 cm and thickness of 3 mm area of the surface to be treated was 8 cm2 The samples prior to application of oxide coating by mAo method underwent mechanical polishing and had roughness of Ra = ndash 0098 μm

Oxide coating was formed in electrolyte so-lution consisting of gl Na2hpo4middot12Н2О ndash 40 na2b4o7middot10 Н2О ndash 30 H3bo3 ndash 20 naF ndash 10 Electrolyte was prepared out of distilled water and analytically pure and chemically pure reagents Mi-cro-arc oxidation was carried out in a 700 ml capac-ity tub made of stainless steel With the purpose of cooling the electrolyte the tub was provided with water cooling system Tub body served as cathode in the process of mAo

mAo process was performed using pulse power source which allowed obtaining voltage pulses of rec-tangular trapezoidal form with pulses flow frequency of 50 Hz and current density of 114ndash130 Adm2

roughness of coatings was measured with ap-plication of proximity MICRO MEASURE 3D sta-tion 3D-profiler Micro-hardness of coatings was identified by means of Nano Hardness Tester by in-denting the penetrator with diamond tip under max-imum load of 20 mn wear resistance of coating was measured on high temperature friction gauge THT-S-AX0000 Identification of coating durabil-ity was based on friction principle of ball indentor made of ВК alloy against surface Whereas the load was equal to 1N linear velocity ndash 25 cms meas-urements were taken under temperature of 250 degc 50 air humidity Durability value was identified by track area measured on three-dimensional profil-er using mountains map universal software and ob-taining three-dimensional images of sample surface with track For each sample 9 values of track area were obtained and arithmetic average was found Coatings thickness was measured on QuaNix-1500 thickness gauge the thickness was calculated as an average among 15 measurements from both sides of the sample Porosity form distribution of pores

by dimension were analyzed by processing micro-photos of surface of samples being studied which photos were obtained on Quanta 200i 3D raster type electronic microscope using planimetry secant and dots methods as a ratio of pore image area to total area of a section under observation [4]

Discussion of results conducting of mAo process in constant current mode causes intense warming up of near-electrode layer which leads to formation of partial melting on the sample surface destruction and peeling of coating formation of coatings with high roughness

It is known that when forming oxide coating by micro-arc oxidation method in the pulse mode the value of current anode pulse duration has a sig-nificant impact on coating roughness [5] In case the process is carried out with small values of cur-rent anode pulse duration the micro-arc charges arise during short period of time in this case the material under treatment is not overheated and in the interval between pulses the heat is able to flow to the solution small values of pulse duration lead to appearance of small oxide buildups and to sig-nificant quantity of pores per unit of area This fa-cilitates formation of uniform coatings with low roughness

Voltage value influences final thickness of the coating values of current anode pulse duration in-fluences coating quality in particular roughness thereof whereas pulse amplitude influences the coating formation rate changes of thickness and roughness of coatings formed under polarizing volt-age Up = 300V under different duration of current anode pulse are in table 1

As it is seen from the obtained data with increase in current anode pulse duration the coating thickness grows coating roughness increases the latter is re-lated to the fact that with growth of coating thickness increases power intensity of micro-plasma charges whereas increase in dimensions of individual micro-arc charges is observed warming up takes place in near-electrode layer of the solution

In the process of study of these coatings for wear resistance (durability) three dimensional im-ages of samples surface with track were obtained on these pictures it is seen that track width of initial sample without coating exceeds the width of tracks of samples with oxide coating obtained under dif-ferent current anode pulse duration

track areas values for samples without coating and with oxide coating are shown in form of a dia-gram in figure

As it is seen from the diagram track areas of samples with oxide coating are significantly less than track area of initial sample which testifies of high wear resistance of samples with oxide coat-ing As anode pulse duration increases with coat-ing thickness growth the coating wear resistance increases since coating roughness is related to fric-tion ratio along with roughness increase friction ratio increases as well (table 2)

EUROPEAN JOURNAL OF NATURAL HISTORY 4 2015

34 Technical sciences

Table 1Dependence of thickness and roughness of coatings on current anode pulse duration

current anode pulse duration ms time min Coating thickness μm Roughness Ra μm1 50 20 78 0342 100 20 111 0573 150 20 197 0924 200 20 265 221

Track areas values when performing durability test of samples without coating and with oxide coating obtained under different durations of current anode pulse 1 ndash initial sample 2 ndash 50 ms 3 ndash 100 ms 4 ndash 150 ms 5 ndash 200 ms

Table 2micro-hardness of coating

polarizing voltage v current anode pulse duration ms micro-hardness mpa Friction ratio1 300 50 15227 0852 300 100 18882 1123 300 150 37757 2164 300 200 335439 368

An important physical and mechanical feature of coating is its micro-hardness micro-hardness values on surface of samples depending on coating obtainment modes are shown in table 2

Study of micro-hardness deep into the sample showed that in the MAO process a transient layer deep into the metal is generated from oxide layer with gradual decrease of micro-hardness value For instance when pulse duration is 100 ms the micro-hardness of transient layer gradually decreases from 10474 MPa to 8462 MPa when measuring at depth of 15 to 40 μm deep into the metal Micro-hardness of initial material is equal in this case to around 150 mpa in this depth interval also young module increase is observed which is below 89 Gpa in av-erage whereas initial material has young module of 70 Gpa

Research of coating surface morphology by means of raster electronic microscope showed that with 50 ms anode pulse duration a thin coating is formed due to low productivity of the process Whereas formation of basic external functional layer is not complete coating is formed in spots with current anode pulse duration of 50 ms forma-tion of significant quantity of round shaped pores per unit of surface area is observed As current an-ode pulse duration increases to 200 ms the nature of micro-plasma charges change small spark charges are replaced with large ones coating thickness growth leads to of refilling pores quantity of pores decreases As a result of spark charges enlargement the average dimension of pores increases with cur-rent anode pulse duration of 200 ms surface poros-ity values are shown in table 3

EUROPEAN JOURNAL OF NATURAL HISTORY 4 2015

35Technical sciences

conclusionsimpact of current anode pulse duration on prop-

erties of oxide coatings has been studied It has been shown that current anode pulse duration has signifi-cant impact on coating roughness As pulse duration increases coating roughness friction ratio increase as well

tribometric research of coatings showed that as a result of micro-arc oxidation durable coatings are formed whereas with increase of anode pulse duration and thickness of coating the durability of the coating increases micro-hardness on coating thickness of 197 and 265 μm is equal to 38 and 335 GPa respectively It has been found out that as a result of micro-arc oxidation a transient layer is formed deep into the metal with high value of micro-hardness in comparison with untreated alu-minum Micro-hardness of transient layer is gradu-ally decreasing deep into the metal

Authors of the article express thanks to Profes-sor Mamayev AI as well as to the Center for ma-terial properties research of the physical-technical institute of Tomskiy polytechnic university to Ka-zakhstan national university named after Al-Farabi for conducting tests of obtained oxide coatings

the work has been performed within frames of grant financing by the Republic of Kazakhstan Min-istry of Education and Science

References1 Kurze P et all Micro Arc Spark Anodizing ndash was ist

das Micro Arc Spark Anodizing ndash what is that Galvanotech-nik 2003 ndash 8 ndash Р 1850ndash1863

2 Mamayev AI Mamayeva VA Intense current pro-cesses in solutions of electrolytes ndash Novosibirsk Edition of Sybirian Department of Russian Academy of Science 2005 ndash 255 p (russ)

3 Suminov IB Epelfeld AB Lyudin VB and other Mi-cro-arc oxidation Theory technology equipment M ECOM-ET 2005 ndash 368 p (Russ)

4 Saltykov SA Stereometric metallography ndash M Metal-lurgy 1970 ndash 375 p (Russ)

5 Chubenko AK Mamayev AI Budnitskaya YY Doro-feyeva TI Role of current pulse duration as a factor of controlling physical and mechanical characteristics of anode-oxide coatings using the example of Д16 aluminum alloy Scientific-technical newsletter of Volga region ndash 2013 ndash 2 ndash Р 62ndash64 (Russ)

the work is submitted to the international sci-entific Conference ldquo Manufacturing technologiesrdquo itAly (rome Florence) september 5ndash12 2015 came to the editorial office оn 11082015

Table 3Surface porosity of oxide coatings

current anode pulse duration ms

coating thick-ness μm

Porosity ΔS Quantity of pores per 1 cm2 of coating

Average diameter of pores μm

1 50 78 64 11106 2722 100 111 117 73105 453 150 197 56 35105 454 200 265 87 302105 606

EUROPEAN JOURNAL OF NATURAL HISTORY 4 2015

34 Technical sciences

Table 1Dependence of thickness and roughness of coatings on current anode pulse duration

current anode pulse duration ms time min Coating thickness μm Roughness Ra μm1 50 20 78 0342 100 20 111 0573 150 20 197 0924 200 20 265 221

Track areas values when performing durability test of samples without coating and with oxide coating obtained under different durations of current anode pulse 1 ndash initial sample 2 ndash 50 ms 3 ndash 100 ms 4 ndash 150 ms 5 ndash 200 ms

Table 2micro-hardness of coating

polarizing voltage v current anode pulse duration ms micro-hardness mpa Friction ratio1 300 50 15227 0852 300 100 18882 1123 300 150 37757 2164 300 200 335439 368

An important physical and mechanical feature of coating is its micro-hardness micro-hardness values on surface of samples depending on coating obtainment modes are shown in table 2

Study of micro-hardness deep into the sample showed that in the MAO process a transient layer deep into the metal is generated from oxide layer with gradual decrease of micro-hardness value For instance when pulse duration is 100 ms the micro-hardness of transient layer gradually decreases from 10474 MPa to 8462 MPa when measuring at depth of 15 to 40 μm deep into the metal Micro-hardness of initial material is equal in this case to around 150 mpa in this depth interval also young module increase is observed which is below 89 Gpa in av-erage whereas initial material has young module of 70 Gpa

Research of coating surface morphology by means of raster electronic microscope showed that with 50 ms anode pulse duration a thin coating is formed due to low productivity of the process Whereas formation of basic external functional layer is not complete coating is formed in spots with current anode pulse duration of 50 ms forma-tion of significant quantity of round shaped pores per unit of surface area is observed As current an-ode pulse duration increases to 200 ms the nature of micro-plasma charges change small spark charges are replaced with large ones coating thickness growth leads to of refilling pores quantity of pores decreases As a result of spark charges enlargement the average dimension of pores increases with cur-rent anode pulse duration of 200 ms surface poros-ity values are shown in table 3

EUROPEAN JOURNAL OF NATURAL HISTORY 4 2015

35Technical sciences

conclusionsimpact of current anode pulse duration on prop-

erties of oxide coatings has been studied It has been shown that current anode pulse duration has signifi-cant impact on coating roughness As pulse duration increases coating roughness friction ratio increase as well

tribometric research of coatings showed that as a result of micro-arc oxidation durable coatings are formed whereas with increase of anode pulse duration and thickness of coating the durability of the coating increases micro-hardness on coating thickness of 197 and 265 μm is equal to 38 and 335 GPa respectively It has been found out that as a result of micro-arc oxidation a transient layer is formed deep into the metal with high value of micro-hardness in comparison with untreated alu-minum Micro-hardness of transient layer is gradu-ally decreasing deep into the metal

Authors of the article express thanks to Profes-sor Mamayev AI as well as to the Center for ma-terial properties research of the physical-technical institute of Tomskiy polytechnic university to Ka-zakhstan national university named after Al-Farabi for conducting tests of obtained oxide coatings

the work has been performed within frames of grant financing by the Republic of Kazakhstan Min-istry of Education and Science

References1 Kurze P et all Micro Arc Spark Anodizing ndash was ist

das Micro Arc Spark Anodizing ndash what is that Galvanotech-nik 2003 ndash 8 ndash Р 1850ndash1863

2 Mamayev AI Mamayeva VA Intense current pro-cesses in solutions of electrolytes ndash Novosibirsk Edition of Sybirian Department of Russian Academy of Science 2005 ndash 255 p (russ)

3 Suminov IB Epelfeld AB Lyudin VB and other Mi-cro-arc oxidation Theory technology equipment M ECOM-ET 2005 ndash 368 p (Russ)

4 Saltykov SA Stereometric metallography ndash M Metal-lurgy 1970 ndash 375 p (Russ)

5 Chubenko AK Mamayev AI Budnitskaya YY Doro-feyeva TI Role of current pulse duration as a factor of controlling physical and mechanical characteristics of anode-oxide coatings using the example of Д16 aluminum alloy Scientific-technical newsletter of Volga region ndash 2013 ndash 2 ndash Р 62ndash64 (Russ)

the work is submitted to the international sci-entific Conference ldquo Manufacturing technologiesrdquo itAly (rome Florence) september 5ndash12 2015 came to the editorial office оn 11082015

Table 3Surface porosity of oxide coatings

current anode pulse duration ms

coating thick-ness μm

Porosity ΔS Quantity of pores per 1 cm2 of coating

Average diameter of pores μm

1 50 78 64 11106 2722 100 111 117 73105 453 150 197 56 35105 454 200 265 87 302105 606

EUROPEAN JOURNAL OF NATURAL HISTORY 4 2015

35Technical sciences

conclusionsimpact of current anode pulse duration on prop-

erties of oxide coatings has been studied It has been shown that current anode pulse duration has signifi-cant impact on coating roughness As pulse duration increases coating roughness friction ratio increase as well

tribometric research of coatings showed that as a result of micro-arc oxidation durable coatings are formed whereas with increase of anode pulse duration and thickness of coating the durability of the coating increases micro-hardness on coating thickness of 197 and 265 μm is equal to 38 and 335 GPa respectively It has been found out that as a result of micro-arc oxidation a transient layer is formed deep into the metal with high value of micro-hardness in comparison with untreated alu-minum Micro-hardness of transient layer is gradu-ally decreasing deep into the metal

Authors of the article express thanks to Profes-sor Mamayev AI as well as to the Center for ma-terial properties research of the physical-technical institute of Tomskiy polytechnic university to Ka-zakhstan national university named after Al-Farabi for conducting tests of obtained oxide coatings

the work has been performed within frames of grant financing by the Republic of Kazakhstan Min-istry of Education and Science

References1 Kurze P et all Micro Arc Spark Anodizing ndash was ist

das Micro Arc Spark Anodizing ndash what is that Galvanotech-nik 2003 ndash 8 ndash Р 1850ndash1863

2 Mamayev AI Mamayeva VA Intense current pro-cesses in solutions of electrolytes ndash Novosibirsk Edition of Sybirian Department of Russian Academy of Science 2005 ndash 255 p (russ)

3 Suminov IB Epelfeld AB Lyudin VB and other Mi-cro-arc oxidation Theory technology equipment M ECOM-ET 2005 ndash 368 p (Russ)

4 Saltykov SA Stereometric metallography ndash M Metal-lurgy 1970 ndash 375 p (Russ)

5 Chubenko AK Mamayev AI Budnitskaya YY Doro-feyeva TI Role of current pulse duration as a factor of controlling physical and mechanical characteristics of anode-oxide coatings using the example of Д16 aluminum alloy Scientific-technical newsletter of Volga region ndash 2013 ndash 2 ndash Р 62ndash64 (Russ)

the work is submitted to the international sci-entific Conference ldquo Manufacturing technologiesrdquo itAly (rome Florence) september 5ndash12 2015 came to the editorial office оn 11082015

Table 3Surface porosity of oxide coatings

current anode pulse duration ms

coating thick-ness μm

Porosity ΔS Quantity of pores per 1 cm2 of coating

Average diameter of pores μm

1 50 78 64 11106 2722 100 111 117 73105 453 150 197 56 35105 454 200 265 87 302105 606